The present invention relates to a mixing apparatus to be used for a laser light source and an optical rangefinder using the same, and more particularly to a mixing apparatus using a phase plate in eccentricity and an optical rangefinder using the same.
In the prior art, there is an optical rangefinder or the like using a laser diode in a light source, whereby measurement with high accuracy becomes possible. The laser diode used in the light source has problems in that when laser rays are emitted, waveform irregularity is not inevitable and the waveform is different depending on angle of emission.
In view of such problems, mixing apparatuses to eliminate the waveform irregularity in the laser light source have been developed. Such a mixing apparatus is disclosed, for example, in Japanese Patent Laid-open No. Sho 63-216003. Here, referring to FIG. 16, the mixing apparatus disclosed in Japanese Patent Laid-open No. Sho 63-216003 will be described.
In the prior art mixing apparatus, light emitted from a semiconductor laser (1) is coupled with an optical fiber (3) of step index type by a condenser lens (2). The optical fiber (3) is wound around an optical fiber vibration device constituted by a motor (4), an arm (5) and a roller (6). The light passing through the optical fiber is emitted from an emission end (3b). When the motor (4) is rotated, the abutment position between the roller (6) and the optical fiber (3) is varied and vibration is produced in the optical fiber (3).
Since the strain position of the optical fiber (3) is varied by the vibration and the total internal state within the optical fiber (3) is varied, the light waveform irregularity is mixed at the emission end (3b).
In the mixing apparatus disclosed in Japanese Patent Laid-open No. Sho 63-216003, however, since the abutment position of the roller (6) is varied due to the rotation of the motor (4), the optical fiber (3) is always bent and stretched repeatedly, whereby a problem exists in that there is apprehension about the durability of the optical fiber (3).
Further since the motor (4) driving the roller (6) is always subjected to the torque due to the bending and stretching of the optical fiber (3), a problem exists in that the consumption power of the motor (4) becomes large.
Also since the vibration produced from the mixing apparatus can not be ignored, when the mixing apparatus is applied to the optical rangefinder, the conclusive vibration measure is necessary and the cost becomes high.
In the present invention, the external distance measurement optical path leads the light from the light source part passing through an article to be measured to the light receiving part, and the internal distance measurement optical path leads the light source part not passing through an article to be measured to the light receiving part, and processing means calculates the distance to the article to be measured from the difference between the distance value obtained by the external distance measurement optical path and the distance value obtained by the internal distance measurement optical path, and the mixing apparatus has the drive means for driving the phase plate.